Four rice mutant strains were crossed in all possible combinations excluding their reciprocals. F₁s of these crosses, their parents (i.e. mutants) and one check variety Srilanka were grown in RBD with three replications. Observations were recorded on plant height, number of panicles plant^-1, panicle length, number of grains panicle^-1, grain density, grain yield and days to 50% flowering. All the characters showed significant variations amongst the genotypes. Hybrids showed higher mean performance than their parents for almost all the characters. Both positive and negative heterosis were observed amongst the hybrids. The expression of heterosis varied with the crosses and characters. Two crosses MS₁´MS₂ and MS₂MS₄ were identified for exploitation of heterosis and to isolate desirable segregants in later generations. Grains panicle^-1 played important role in the expression of heterosis.